The present invention relates to communication systems and more particularly to multicouplers for interfacing multiple transceivers to a single antenna.
Modern military communications systems require a high level of anti-jam protection which is primarily achieved through spread spectrum techniques such as frequency hopping. In such systems, the frequency of operation of transmitter and corresponding receiver units rapidly change in unison or "hop" from one frequency to another over a broad frequency range such as 30-88 MHz in order to make it more difficult for their transmissions to be jammed. However, this type of frequency agility causes design problems when multiple transceivers are co-located at a single site and must use the same antenna for broadcasting their separate signals. In the past, this problem had been solved by employing multicouplers using slow-tuning mechanical filters which allowed for the required isolation between the transceiver modules. Unfortunately, mechanically tuned filters are simply not fast enough to track the hopping patterns of frequency-agile transceivers. Therefore, a new generation of frequency-agile multicouplers is required which can track frequency hopping patterns while providing the isolation, low insertion loss and high selectivity otherwise required of multicouplers for interfacing two or more transceivers to a single antenna.
It is, therefore, an object of the present invention to provide a multicoupler for interfacing multiple transceivers to a single antenna which is capable of rapidly tracking the hopping patterns of modern frequency-agile transceivers and which comprises a moderately sized structure which may be manufactured at a reasonable cost.
It is another object of the present invention to provide a frequency-agile multicoupler which provides good isolation between the transceivers to which it is connected, low insertion loss for signals passing through the multicoupler and high selectivity for insuring the spectral purity of signals transmitted through the filters of the multicoupler.
It is a further object of the present invention to provide a frequency-agile multicoupler which is constructed and arranged for producing very low levels of intermodulation distortion in the signals passed through the multicoupler.